The increased number of cancer cases reported in the United States, and, indeed, around the world, is a major concern. Currently there are only a handful of detection and treatment methods available for some specific types of cancer, and these provide no absolute guarantee of success. In order to be most effective, these treatments require not only an early detection of the malignancy, but a reliable assessment of the severity of the malignancy.
It is apparent that the complex process of tumor development and growth must involve multiple gene products. It is therefore important to define the role of specific genes involved in tumor development and growth and identify those genes and gene products that can serve as targets for the diagnosis, prevention, and treatment of cancers.
In the realm of cancer therapy, it often happens that a therapeutic agent that is initially effective for a given patient becomes, over time, ineffective or less effective for that patient. The very same therapeutic agent may continue to be effective over a long period of time for a different patient. Further, a therapeutic agent that is effective, at least initially, for some patients can be completely ineffective or even harmful for other patients. Accordingly, it would be useful to identify genes and/or gene products that represent prognostic genes with respect to a given therapeutic agent or class of therapeutic agents. It then may be possible to determine which patients will benefit from particular therapeutic regimen and, importantly, determine when, if ever, the therapeutic regime begins to lose its effectiveness for a given patient. The ability to make such predictions would make it possible to discontinue a therapeutic regime that has lost its effectiveness well before its loss of effectiveness becomes apparent by conventional measures.
Recent advances in the understanding of molecular mechanisms of oncogenesis have led to exciting new drugs that target specific molecular pathways. These drugs have transformed cancer treatments, especially for those caused by some specific oncogenic events, such as Herceptin for breast cancer, caused by HER2/Neu, and Gleevec for chronic myelogenous leukemia caused by Bcr-Abl. However, it has been increasingly evident that, in many individual tumors, there are a large number of mutated genes that disrupt multiple interactive and/or redundant pathways. Thus, intervening in a single pathway may not be effective. Furthermore, cancer resistance to molecularly targeted drugs can develop through secondary target mutation or compensatory activation of alternative pathways, so-called “oncogenic switching.” Thus, a major challenge remains how to simultaneously inhibit multiple oncogenic pathways either using a combination of multiple drugs, with each acting on a specific pathway, or using a single drug that concurrently blocks multiple pathways. The results disclosed herein suggest that Pin1 inhibitors might have a major impact on treating cancers, especially aggressive and/or drug-resistant cancers.
We and others have shown that Pin1 is prevalently overexpressed in human cancers and that high Pin1 marker levels correlate with poor clinical outcome in many cancers. In contrast, the Pin1 polymorphism that reduces Pin1 expression is associated with reduced cancer risk in humans. Significantly, Pin1 activates at least 19 oncogenes/growth enhancers, including β-catenin, cyclin D1, NF-κB, c-Jun, c-fos, AKT, A1B1, HER2/Neu, MCl-1, Notch, Raf-1, Stat3, c-Myb, Hbx, Tax, and v-rel, and also inactivates at least 12 tumor suppressors/growth inhibitors, including PML, SMRT, FOXOs, RARα, and Smad (FIGS. 1A and 1B). Whereas Pin1 overexpression causes cell transformation and tumorigenesis, Pin1 knockdown inhibits cancer cell growth in cell cultures and mice. Pin1-null mice are highly resistant to tumorigenesis induced either by oncogenes such as activated Ras or HER2/Neu, or tumor suppressors such as p53. Thus, Pin1 inhibitors might have the desired property to suppress numerous oncogenic pathways simultaneously for treating cancers, especially those aggressive and/or drug-resistant cancers.